Concrete blocks intended to serve as paving units (e.g., pavers, paving tiles, etc.), wall construction units (e.g., masonry units, retaining wall units, etc.), ornamental blocks, steps, and other landscaping elements are sometimes provided with a natural stone appearance over an exposed portion thereof. Such concrete blocks can then be assembled into paved surfaces, walls or other structures that have a natural and aesthetic look.
Depending on their constituent concrete, concrete blocks can be broadly divided into dry-cast concrete blocks and wet-cast concrete blocks. Different processes are used to manufacture these two types of concrete blocks and, in particular, to provide them with a natural stone appearance.
Wet-cast concrete blocks may have a natural stone appearance realized directly during casting, but relatively long production times and requirements for numerous molds typically render impractical their efficient mass-production. For their part, dry-cast concrete blocks normally have relatively short production times and require only one or a few molds, which facilitates their mass-production. However, these relatively short production times impose constraints on a degree of surface irregularity that may be imparted to dry-cast concrete blocks during casting, thereby preventing realization of a natural stone appearance during casting. Dry-cast concrete blocks are thus typically subjected after casting to a mechanical artificial aging/weathering process (e.g., tumbling, splitting/breaking, object impacting, etc.) to realize desired natural stone characteristics, which decreases production efficiency.
There is therefore a need for dry-cast concrete blocks for which a natural stone appearance is obtained during casting.